Research has conventionally been directed to development of methods for treating organic drain water using aerobic microorganisms. In one example of such research and development, kitchen garbage discharged from houses or the like is crushed using a disposer to be processed together with kitchen drain water as drain water containing kitchen garbage.
The inventor of the present invention previously proposed a kitchen garbage processing apparatus performing the following procedures. A disposer crushes kitchen garbage discharged from a kitchen. A mixture of the crushed kitchen garbage and kitchen drain water is temporarily collected in a flow-rate adjustment tank. The drain water supplied from the flow-rate adjustment tank is separated into a solid portion and a liquid portion. The solid portion is processed into compost using a compost-producing device (solids processor). After particles within the liquid portion are separated through precipitation in a precipitation tank, the remaining supernatant, or organic drain water, is subjected to aerobic biological treatment (hereinafter referred to simply as “aerobic treatment”) in treatment columns filled with a carrier carrying microorganisms (referred to as “microorganism carrier”), and finally drained.
However, the organic drain water supplied to the above treatment column contains fine suspended solids of kitchen garbage, which cause frequent clogging of the microorganism carrier in the treatment column.